The Interaction Between Oxygen and Vascular Wall
During the last decade the important role of endothelium in the local control of vascular smooth muscle function has become more and more evident. In response to various chemical and physical stimuli, vascular endothelial cells synthesize and release substances which can induce changes in tone of the underlying smooth muscle cells (1,5,17,20,24,25,27). In addition, due to the uptake and the enzymatic conversion or breakdown of several circulating vasoactive substances, endothelium influences their activity in vascular smooth muscle (s. 25). Oxygen metabolites are able to influence or even disrupt these functions. Various reactive intermediates of oxygen metabolism cause characteristic changes in the metabolism of the vascular endothelial cells and induce e.g. an increased production of certain arachidonic acid metabolites (4,11,19,25). In vitro experiments suggest that oxidizing free radicals facilitate the release of the endo-thelium-derived relaxing factor(s) (EDRF) and a smooth muscle relaxation while superoxide anions depress the EDRF mediated decrease in smooth muscle tone (s. 25). Following exposure to a variety of free radicals, endothelial cell lesions, most frequently in the area of intercellular junctions, and also cytolysis were observed (11-13).
KeywordsVascular Smooth Muscle Vascular Smooth Muscle Cell Oxygen Tension Arachidonic Acid Metabolite Smooth Muscle Tone
Unable to display preview. Download preview PDF.
- 7.J. Grote and R. Schubert, Regulation of cerebral perfusion and PO2 in normal and edematous brain tissue, In: J.A. Loeppky, M.L. Riedesel, (eds.), Oxygen Transport to Human Tissue, Elsevier North Holland, Amsterdam, New York, Oxford, pp.169–178 (1982).Google Scholar
- 21.G. Siegel, Membranphysiologische Grundlagen der peripheren Gefäßregulation, Physiologie aktuell 1:31–52 (1986).Google Scholar
- 22.G. Siegel, R. Ehehalt, and H.P. Koepchen, Membrane potential and relaxation in vascular smooth muscle, in.: P.M. Vanhoutte, I. Leusen, (eds.), Mechanisms of Vasodilatation, Karger, Basel, pp. 56–72 (1978).Google Scholar
- 26.E.P. Wei, E.F Ellis and H.A. Kontos, Role of prostaglandins in pial arteriolar response to CO2 and hypoxia, Am. J. Physiol. 238:H226–H230 (1980).Google Scholar